In recent years, products having a face detection function of detecting the face of a person as one of the subject detection functions are increasing in digital cameras. Moreover, for example, products have also been developed which focus on a subject designated by a photographer by detecting the subject using feature point extraction, color extraction, or the like so that the focus follows the subject even if the subject moves within a screen, and these products are commercially available. That is, it is possible to make the focus follow the subject automatically through the subject detection function and the AF (Auto Focus) function.
There are many digital cameras with a face detection function, and various techniques for detection of an image of the face of a person have been developed. For example, a technique of determining the focus position at high speed on the basis of the size of the face has also been proposed by applying the technique of extracting a person from the image data to cameras (for example, refer to PTL 1).
In a digital camera with such a face detection function, the AF function works such that when a person as a subject moves within the screen, the focus follows the face of the person, for example. Moreover, in the digital camera, the AF function works such that the focus follows the face of a person even if a zooming operation is performed.